问题 选择题

有一个负点电荷只受电场力的作用,分别从两电场中的a点由静止释放,在它沿直线运动到b点的过程中,动能随位移S变化的关系图象如左下图中的①、②图线所示,则能与图线相对应的两个电场的电场线分布图分别是下图中的:(       )

答案

B C

本题考查场强的大小和方向,电场力做功等于动能的变化量,由图像可知图线1的动能与位移s成正比,说明电场力恒定不变,为匀强电场,并且电场力做正功,电场力方向与运动方向相同,B对;图线2斜率增大说明电场力增大,场强增大,并且电场力也做正功,C对;

点评:小综合题一直是高考题的热点,本题中利用了电场模型考到了动能定理的应用,根据动能的增大或减小判断电场力方向,根据斜率判断电场力大小变化情况,从而判断场强方向

阅读理解

Many teenagers feel that the most important people in their lives are their friends. They believe that their family members, and in particular, their parents, don’t know them as well as their friends do. In large families, it is quite often for brothers and sisters to fight with each other and then they can only go to their friends for advice.

It is very important for teenagers to have one good friend or a circle of friends Even when they are not with their friends, they usually spend a lot of time talking among them on the phone. This communication is very important in children’s growing up, because friends can discuss something difficult to say to their family members.

However, parents often try to choose their children’s friends for them. Some parents may even stop their children from meeting their good friends. The question of “choice” is an interesting one.

Who chooses your friends?

Do you choose your friends or your friends choose you?

Have you got a good friend your parents don’t like?

Your answers are welcome.

小题1:Many teenagers think their ________ know them better than their parents do.

A.friends

B.brothers

C.sisters

D.teachers小题2:When teenagers stay alone, their usual way of communication is ________.

A.to go to their friends

B.to talk with their parents

C.to have a discussion with their family by phone

D.to talk with their friends on the phone小题3:Which of the following is different in meaning from the sentences “Some parents may even stop their children from meeting their friends?

A.Some parents may even not allow their children to meet their good friends.

B.Some parents may even ask their children to stay away from their good friends.

C.Some parents may even not let their children meet their good friends.

D.Some parents may want their children to meet their good friends at the stop.小题4:Which of the following sentences is right according to the passage?

A.Parents should like everything their children enjoy.

B.In all families children can choose everything they like.

C.Parents should try their best to understand their children better.

D.Teenagers can only go to their friends for help.小题5:The sentence “Your answers are welcome” means“________”.

A.You are welcome to have a discussion with us.

B.We’ve got no idea, so your answers are welcome.

C.Your answers are always correct.

D.You can give us all the right answers.小题6:Which is the best title of the passage?

A.Only Parents Can Decide

B.Parents and Children

C.Teenagers Need Friends

D.A Strange Question

多项选择题